Electric signal code generator



y 23, 1968 E. A. WESTPHAL 3,385,943

ELECTRIC SIGNAL CODE GENERATOR Filed May 2. 1967 2 Sheets-Sheet 1 :fls[9 2| [6 l7 FIG. I FIG. 2

INVENTOR EVERETT A. WESTPHAL 4 WM, f/hfim,

HIS ATTORNEYS May 28, 1968 E. A. WESTPHAL ELECTRIC SIGNAL CODE GENERATOR2 Sheets-Sheet ti Filed May 2, 1967 FIG FlG

INVENTOR L A H P T r s E W i S Y E T N T R E m R 7 WW s H Y B UnitedStates Patent "ice 3,385,943 ELECTRIC SIGNAL CODE GENERATOR Everett A.Westphal, Lafayette, Calif. (325 7th t, Oakland, Calif. 94607) Filed May2, 1967, Ser. No. 635,562 5 Claims. (Cl. 200-166) ABSTRACT OF THEDISCLOSURE An electrical signal code generator wherein an electricalcircuit is interrupted according to a desired pattern includes a wheelcarrying two mutually insulated contacts, at least one of which is aring of separated contacts wiped by a brush, each of which is connectedto a second contact element on the wheel by severable electricalconnectors which can be selectively severed, as by drilling, to breakthe connection and form a desired code. The second contact element canbe continuous or interrupted and can be wiped by a second brush or haveexternal electrical contact through the wheel axle. Several pairs ofsuch contacts can be provided to adapt the wheel to an alarm system,e.g., suitable for use in a McCulloh loop.

The invention relates to an electrical signal code generator which canmake and/or break an electrical circuit in accordance with a desiredpattern to generate a code in one or in a plurality of circuits. Moreparticularly, it relates to a generator of the type having a wheel whichis rotatable relatively to one or more brushes which wipe electricalcontacts on the wheel, wherein the wheel can be easily altered togenerate any of a large number of codes.

The invention is applicable, for example, to alarm systems in which aplurality of remote subscribers premises to be protected from burglary,fire, or the like are connected by electrical circuits, such astelephone lines or radio channels, to a central office whereat thesignals are received and recorded in the vent of an unauthorized entryor a fire at the subscribers premises. In a special application, each ofthe subscribers lines is connected to the central otfice by what isknown as a McCulloh loop circuit. This circuit, being well known, willnot be described herein in detail; it includes, at the central oflice,an electrical storage battery, the positive side of which is groundedand which is connected at both sides through coils of relays to theline, these relays being connected to recognize either the opening orthe grounding of the circuit. Several subscribers lines are connected toa common central ofilce receiver and recorder, for example, connected inseries, and the identity of the subscriber emitting a signal isrecognized by the particular code. In this system, each code generatorat a subscribers premises has a circuit switch which is normally closedso that opening or grounding of the circuit at any subscriber will bemanifested at the central office.

In the code generators used heretofore, each mechanism included a pairof spring arms controlling switchpoints, of which one was normallyclosed and the other, leading to ground, was normally open, theseswitches being actuated by a cam wheel having a series of notchesarranged according to a predetermined pattern. In the event of anyunauthorized opening of a circuit at the subscribers premises, a relayat those premises becomes tie-energized, which thereby energizes a motordrive to operate the notched wheel, causing the switches to send codedpulses over the telephone line to the central ofiice registers.

A drawback of the known code generating switch mech- 3,385,943 PatentedMay 28, 1968 anism has been the need to provide a large number ofdifferent cams for actuating the switches or the difiiculty in cutting acam wheel having properly spaced notches for each installation. It isevident that when several subscribers are connected in series each musthave a different code.

A further drawback has been that the cam mechanism does not alwaysproduce pulses of uniform duration or occurring at preciselypredetermined intervals. Thus, a slight misalignment of the drive shaftof the notched wheel or a slight deformation of the spring fingers whichcooperate with these notches leads to nonuniform operation. This hasrequired the spring arms to be carefully adjusted at each installation,which is a time-consuming operation. Moreover, such mechanisms aresubject to rapid wear and frequent servicing is necessary.

According to the present invention, these drawbacks are avoided byproviding a code generator having a wheel in which any desired code canbe readily set up by merely severing connections between electricalcontacts on the wheel. The dimensions of these contacts can be carefullycontrolled during manufacture, leading to improved uniformity of pulses.Moreover, such a device does not need any adjustment and, by providingthe contacts with suitable wear-resistant surfaces, a long service lifeis assured.

In summary, according to the invention, the code generator includes awheel carrying at least one pair of contacts, of which at least one is aring of separated contacts wiped by a brush, each of said contacts beingconnected to a second contact element (which may be continuous ordiscontinuous) by a severable electrical connector which is adapted tobe easily cut, as by drilling, to break the connection between theseparated contact and the second contact on the wheel. The secondcontact element may also be wiped by a brush or, if desired, anelectrical circuit thereto can be established through the shaft of theWheel. Several pairs of such contacts can be provided to adapt the wheelto an alarm system suitable for the above-mentioned McMulloh loop. Theremust, of course, be relative rotation between the wheel and the brushes;however, it is not essential that the wheel ro tate, it being alsopossible to employ a stationary wheel and to rotate the brushes mountedon a suitable pivoted arm.

To facilitate severing the electrical connectors, each is preferablyprovided with a depression for guiding its severing implement, e.g.,each such connector may have a depression for receiving the point of asmall drill which is used to cut away the connection.

Advantageously, the wheel is a flat disc and the contacters are appliedthereto by any known printed circuit technique. Preferably, all contactsthat are wiped by brushes are further plated to make themwear-resistant.

The invention will be further described with reference to theaccompanying drawing forming a part of this specification and showingtwo preferred embodiments, wherein:

FIG. 1 is an elevation of the code-generating device, a part of the basebeing shown in section;

FIG. 2 is an end view of the device;

FIG. 3 is a section taken on the line 3-3 of FIG. 1, showing the face ofthe code wheel, parts of the connecting circuit being shown;

FIG. 4 is an enlarged, fragmentary view of a part of the code wheel;

FIG. 5 is a plan of a code wheel [according to a modified embodiment;

FIG. 6 is a plan of the reverse side of the wheel shown in FIG. 5; and

FIGS. 7 and 8 are fragmentary sectional views taken on the correspondingsection lines of FIG. 5.

Referring to FIGS. 1-4, the code generator comprises a base plate 10having journaled therein a drive shaft 11 which is connected to asuitable electrical motor (not shown) and is secured to a code wheel 12.A pinion gear 13 may be mounted on the shaft 11 for rotation with thewheel 12, e.g., by means of a pin 14 which extends through a hole in thewheel. The gear meshes with another gear (not shown) for controlling theoperation of the drive motor. The parts 10 and 12 may be made of anysuitable, rigid, insulating material, such as plastic or insulatingboard. The base 10 carries a plurality, e.g., four brushes 15-18, whichare mounted in pairs on soldering lugs 19 and 20 which are fastened byrivets to the base 10. These brushes may be Phosphor-bronze wires andextend through holes 21 in the base to engage the face of the wheel 12.These brushes may, for example, have loops at their ends to presentconvex contact regions and bear against the wheel resiliently with apressure of about 2 grams. The pin 14 may be grounded to provide a fifthelectrical circuit to the wheel face.

The face of the wheel 12 against which the brushes 15-18 bear isprovided with suitable contacts which may be applied by theprinted-circuit technique, e.g., being formed principally of coppercoated with a wear-resistant material, such as nickel, as needed.However, the invention is not limited to this specific construction, andthe contacts may be cut from a metallic sheet and applied to the wheelface. Regardless of the technique of manufacture, the contacts providethe following, which will be de scribed in a specific relationshiprelatively to the distance from the periphery of the wheel, although thesequence can be varied as desired At the outside is a ring of separatedcontacts 22, positioned for engagement by the brush 18 and separatedcircumferentially by insulated sections 23. Inside of this ring is acontinuous ring 24, positioned to make continuous contact with the brush16 and having a plurality of radially outwardly extending contactsections 25 positioned to make intermittent contact with the brush 17.Each of the contacts 25 is connected by a severable metallic connector26 to a corresponding separated contact 22. Thereby all of the severalcontacts heretofore described are initially interconnected electrically.Each connector 26 has a guide recess, such as a small tapered depression27, for guiding the point of a drill. When a drill is placed into arecess 27 and a hole is drilled partly into the wheel 12, the connector26 is severed, as indicated at 27a in FIG. 4.

The wheel further has a central metallic area 28 which is electricallyconnected to the pin 14 to establish a ground circuit, and has aplurality of radially outwardly extending contacts 29 positioned forwiping engagement with the brush 15. Each contact 29 is connectedelectrically to the part 28 by a severable connection 30, which issimilarly provided with a recess 31. When a drill is applied to therecess 31, the contact 29 is severed from the region 28, as appears at31a.

The shaft 11 rotates to drive the wheel in the direction indicated bythe arrow 32, and each contact 22 has a leading edge 33 which is alignedradially with the trailing edge 34 of a preceding contact 25. Similarly,each trailing edge 35 of a contact 22 is aligned radially with theleading edge 36 of the corresponding contact 25. It will be understoodthat this alignment is appropriate for the embodiment shown, wherein theseveral brushes 1518 are situated on a common radial line; further, thecontacts 25 may be slightly wider than indicated. The arrangement, inany case, when employed for use in a McCulloh loop circuit, is such thatthe brush 17 engages the contact 25 not after the brush 18 disengagesthe corresponding contact 22, and that the brush 17 breaks contact withthe contact 25 not before the brush 18 engages the next contact 22.Similarly, each contact 29 is aligned with the outer contacts so thatthe brush 15 engages the contact 29 somewhat before the brush 17 engagesthe contact 25 and disengages the contact 29 somewhat before the brush17 leaves the contact 25.

A portion of the circuit which receives the code is illustrated in FIG.3, wherein the brushes 17 and 18 are connected to one side L-l and thebrushes 15 and 16 to the other side L-2 of a telephone line leading tothe central oflice. (When several subscribers are connected to a cornmoncentral ofiice, additional code generators may be connected seriallyinto this telephone circuit.) The central office has relays of whichonly the windings RY-l and RY2 are shown, these relays being furtherconnected to a battery B of which the positive side is gounded.

In operation, the wheel 12 is normally stationary at a home position atwhich the brush 15 engages an insulated area between the contacts 29,the brush 17 engages an insulated area between the contacts 25, and thebrush 18 engages one of the contacts 22; the brush 16 always engages thecontact 24. When the wheel 12 rotates in the direction of the arrow 32,the brush 15 engages the contacts 29 in succession. Upon engaging thosecontacts 29 at which a hole 310 was formed to sever the connector 30,the brush 15 remains ungrounded; however, when the brush engages one ofthe other contacts 29, it is temporarily grounded, thereby de-energizingthe relay winding RY2. Also, in the cases of the connectors 26 which donot have holes 27a drilled out, either the brush 17 or 18 will beelectrically connected to a contact 25 or 22, respectively, whereby thecircuit L-1 is connected to the circuit L-2 via the brush 16 :and thecontact 24. However, when the brush 18 engages a contact 22 which hasits connector 26 severed by a hole 27a, the circuit L-1 is disconnectedfrom the circuit L-2, thereby causing both relays RY1 and RY2 to becomede-energized.

It is evident that by selectively severing the connections 26 and 30 alarge variety of codes or patterns of signals can be provided in thesame code wheel, and that this is easily done by the mere use of :arotary drill.

The invention may be otherwise embodied, and the severable connectorsmay take other forms. For example, in the embodiment shown in FIGS. 5through 8, the code wheel 112 has an outer ring of separated contacts122, a circumferentially continuous contact ring 124 having radiallyoutwardly projecting contacts 125, and an inner ring ofcircumferentia-lly separated contacts 129, all fixed to one face thereofand formed as previously described. Reference numbers in this embodimentdenoting parts which correspond to those of the first embodiment areincreased by one hundred, and the wheel 112 is designed to cooperatewith four brushes similarly aligned along a common radial line. Thereverse side of the wheel 112 carries a continuous metallic conductingring 135. Each of the contacts 122 is electrically connected to the ring135 by a tubular connector 126 having flared outer ends which providetapered recesses 131. The connectors 126 can be selectively removed bydrilling completely or partly through the wheel so as to sever theelectrical connection between the parts 122 and 135. When the wheel isdrilled entirely through, the connector 126 is removed, leaving a hole131a, as appears in FIG. 8. The ring 135 is connected to the continuouscontact 124 by a similar tubular connector 136. The contacts 129 areelectrically connected to a metallic, conductive area 128 on the reverseside of the wheel by tubular connectors 130, which are constructedexactly as previously described for the connectors 126. These can beselectively drilled out to sever the connections 130 and separate thecontacts 129 from the conductive area 128. It will be understood thatthe area 128 is suitably connected to an external circuit, e.g., isgrounded as described for the area 28 in the first embodiment.

The wheel 112 has the various contacts placed in coordinated positionsin accordance with the desired function, e.g., as described for thefirst embodiment, and is rotated in the direction indicated by the arrow132. It is evident that the operation is the same, and that any desiredcode can be generated in accordance with the numbers and locations ofthe connectors and 130 which are severed.

Although severable electrical conductors were described in connectionwith the preferred embodiment, it is evident that the opposite may beused. Thus, the code wheel of either embodiment may be initiallymanufactured with the connections absent, and these can be added insetting up the desired code, as by applying a drop of solder to bridgethe unconnected contacts in the first embodiment or by inserting thetubular connectors 130 as necessary.

I claim:

1. An electrical signal code-generating system which comprises: firstand second brushes, a code wheel rotable relative to said brushes, firstand second mutually insulated contact rings on said Wheel situated tomake electrical contact respectively with the first and second brushes,at least the first ring being discontinuous to form a series of contactsseparated by insulated sections, and electrically conductive meansinterconnecting said contacts to said second ring, said conductive meansbeing the only electrical connections between said rings and beingselectively severable to thereby establish a desired code of sequentialcircuit interruptions between said brushes upon relative rotation ofsaid wheel and brushes, said separated contacts having the trailingedges thereof spaced from the leading edges of the respectively nextcontacts by insulated sections greater in length than the contact lengthof said first brush, said wheel including a third electricallyconductive ring of contacts, said ring being electrically connected tosaid second ring, and a third brush positioned for electrical contactwith said third ring, the contacts of said third ring having leadingedges positioned in coordinated relation to the separated contact,whereby rotation of said whee-1 relative to said brushes causes apredetermined series of circuit interruptions to thereby establish asignal pattern.

2. The apparatus set forth in claim 1, wherein the leading edge of eachcontact of said third ring is situated in relation to the positions ofsaid first and third brushes and of said separated contact so that thecontact of the third ring makes contact with the third brush not afterthe first brush breaks contact with the separated contact and breakscontact with the third brush not before the first brush makes contactwith the next separated contact.

'3. The apparatus as set forth in claim 1, wherein said conductorscomprise strips of metal interconnecting each contact of the third ringwith corresponding separated contacts.

4. The apparatus as set forth in claim 1, wherein the contacts of saidthird ring have radial leading and trailing edges, said edges beingaligned radially respectively with the trailing edge of a separatedcontact and with the leading edge of a succeeding separated contact.

5. The apparatus as set forth in claim 1, wherein a fourth brush isprovided, said wheel having a fourth ring of circumferentially spacedcontacts, said fourth ring being positioned for successive electricalcontact with said fourth brush, a comm-on electrical circuit, andsevera- -ble electrical conductors connecting each of said contacts ofthe fourth ring with said common circuit.

References Cited UNITED STATES PATENTS 3,148,438 9/1964 Winter et al29-626 3,204,236 8/ 1965 Duris et al 340-345 3,261,929 7/1966 Neff 200113,293,399 12/1966 Heinrich 200166 3,320,391 5/1967 Lafont 200166 FOREIGNPATENTS 973,975 t1 1/ 1964 Great Britain.

ROBERT K. SCHAEFER, Primary Examiner. H. O. JONES, Assistant Examiner,

